The demand for multi-band communication systems has increased tremendously, particularly in the public safety arena where the interoperability of different communication systems is highly desirable. Fire departments, medical rescue and law enforcement are just a few examples of agencies that can benefit from the ability to communicate across different systems. The ability of a communication device, such as a radio, cell phone, digital assistant or the like, to operate amongst different frequency bands facilitates seamless mobility for the user.
The design of a multi-band communication device is complex as the different operating specifications for each band need to be addressed. In order to provide multi-band operation, circuit designers have typically increased the number of voltage controlled oscillators and provided multiple loop filters. Variations in frequency, tuning sensitivity, acquisition lock time and loop filter bandwidth are examples of operating parameters that need to be addressed in these circuits. Reduction of parts count and utilization of circuit board space are also of paramount importance in a portable multi-band radio design as these affect the cost, size and weight of each device.
Accordingly, a multi-band approach facilitating the issues discussed above is desirable.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.
The apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.